The National Electrical Code: Ground Fault Circuit Interrupter Protection
The National Electrical Code: Ground Fault Circuit Interrupter Protection
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The National Electrical Code: Ground Fault Circuit Interrupter Protection
Note to the Reader: These articles are based on the latest Revision of the National Electrical Code (NEC), the National Fire Protection Associations (NFPA), Publication 70, 2008 Revision. My reason for writing these articles is to try to make the Electrician’s Bible comprehensible even to the new do-it-yourself electrician.
Ground Fault Circuit Interrupter (GFCI) protection became available in the early 1970s and became part of the NEC with the release of the 1971 Revision, which was accepted by all the states by January 1, 1973. At that time, GFCI protection was only required on exterior electrical receptacles and swimming pools. The NFPA added more areas requiring GFCI protection to the NEC with each revision of the Code. The NFPA added wet bars to the list with their 2008 revision of the code.
Today, GFCI protection is required on:
The NEC recognizes and accepts two means of providing GFCI protection on receptacle devices, GFCI circuit breakers mounted in the service panel and GFCI protector receptacle devices. Ground Fault Circuit Interrupter/Receptacle devices mount in standard device boxes.
Why Does The NEC Require GFCI Protection On Specific Circuits
To understand why GFCI circuit breakers or GFCI interrupter/receptacles are required, you need to know how a GFCI circuit breaker differs from a standard circuit breaker. The circuit breakers (CBs) that everyone are familiar with, like the old Edison Base fuses, protects appliances and wiring against short circuits and circuit overloads. They protect against property damage they do not protect people against ground fault condition. A ground fault occurs when the neutral conductor makes electrical contact with a grounded surface i.e. the metal case of a toaster. The neutral conductor is a grounded conductor, connected to the system ground at the service panel. Ground fault conditions do not present a danger to property, but they are hazardous to people and pets. There would not be a problem except for the fact that electricity has the nasty habit of taking the path of least resistance to ground. The path of least resistance to ground is through your body if you touch the case of a ground faulted appliance and a solid earth ground like the faucets on your kitchen sink. Contrary to popular belief, it is not voltage that kills, but amperes. It takes far less current than you might think to send your heart into arrhythmia. Ground fault circuit interrupters open the circuit with a ground fault current of .005 amperes maximum.
How Does GFCI Work
The simple explanation is, the GFCI device has a differential amplifier built-in to detect and compare the current flowing in both the "Hot" wire and the "Neutral" wire. When the differential amplifier detects a difference in current flow, it sends a signal to a tiny solenoid that trips the circuit open. The "Test" button found on GFCI breakers and GFCI Receptacles simulates a ground fault condition to test the differential amplifier and solenoid circuitry.
GFCI Device Failure Rate
Ground fault circuit breakers and GFCI Receptacles are not as reliable as we would like them to be. According to a study published in the November/December 1999 issue of the International Association of Electrical Inspectors (IAEI) magazine, GFCI devices fail far more often than we might think. The study conducted by the American Society of Home Inspectors (ASHI) presents us with some alarming statistics. More than 21-percent of GFCI circuit breakers and 19-percent of GFCI Receptacles tested did not provide ground fault protection. The failure rate in areas of high-lightening strike was as high as 57 percent. The differential amplifier Integrated Circuit (IC) chip in GFCI is as easily damaged by power surges like any electronic device is, yet lack ant form of surge protection. The alarming thing is that when a GFCI device fails, it continues to pass electric current but no longer protects the unsuspecting homeowner from ground faults conditions.
Routine Inspection And Testing
You should check all ground fault circuit interrupters every 30 days. Testing a GFCI device does not take much time and it could save your life or the life of a loved one. Simply press the "Test" button on the device. If the device is working, as it should, the circuit will go dead. You do not even need a GFCI receptacle tester; all you need is a lamp to plug into the receptacle. Reenergize the circuit by pressing the "Reset" button. Ground fault interrupter CBs and GFCI Receptacles come with a logbook that makes it easy to keep track of when you checked the devices last. If you do not have a logbook make one of your own using a spiral notebook. Give each device an identifying number and a line of its own then date it and initial it every time you test it.
If you do not have GFCI protection on the circuits I listed at the beginning of this article, you need to install it or have a professional electrician install it.